A Mexico massacre in unfamiliar place: the capital

Army soldiers stand around a passenger bus in the northern border city of Ciudad Juarez, Mexico, early Thursday Oct. 28, 2010. According to Arturo Sandoval, a spokesman for the Chihuahua state attorney general's office, a gang opened fire on two passenger buses carrying factory workers, killing four people and injuring more than a dozen. Ciudad Juarez, across the border from El Paso, Texas, has become one of the world's deadliest cities since a turf war erupted nearly three years ago between the Juarez and the Sinaloa cartels. (AP Photo/Raymundo Ruiz)
— AP

Army soldiers stand around a passenger bus in the northern border city of Ciudad Juarez, Mexico, early Thursday Oct. 28, 2010. According to Arturo Sandoval, a spokesman for the Chihuahua state attorney general's office, a gang opened fire on two passenger buses carrying factory workers, killing four people and injuring more than a dozen. Ciudad Juarez, across the border from El Paso, Texas, has become one of the world's deadliest cities since a turf war erupted nearly three years ago between the Juarez and the Sinaloa cartels. (AP Photo/Raymundo Ruiz)
/ AP

Forensic workers stand by the body of a woman lying next to a passenger bus in the northern border city of Ciudad Juarez, Mexico, early Thursday Oct. 28, 2010. According to Arturo Sandoval, a spokesman for the Chihuahua state attorney general's office, a gang opened fire on two passenger buses carrying factory workers, killing four people and injuring more than a dozen. Ciudad Juarez, across the border from El Paso, Texas, has become one of the world's deadliest cities since a turf war erupted nearly three years ago between the Juarez and the Sinaloa cartels. (AP Photo/Raymundo Ruiz)— AP

Forensic workers stand by the body of a woman lying next to a passenger bus in the northern border city of Ciudad Juarez, Mexico, early Thursday Oct. 28, 2010. According to Arturo Sandoval, a spokesman for the Chihuahua state attorney general's office, a gang opened fire on two passenger buses carrying factory workers, killing four people and injuring more than a dozen. Ciudad Juarez, across the border from El Paso, Texas, has become one of the world's deadliest cities since a turf war erupted nearly three years ago between the Juarez and the Sinaloa cartels. (AP Photo/Raymundo Ruiz)
/ AP

MEXICO CITY 
Armed men rumbled into a gritty neighborhood of the Mexican capital Thursday and gunned down six men hanging around a convenience store, fueling fears that one of the world's largest cities is falling prey to the cartel-style violence that has long terrorized other parts of the country.

More than 50 people have been killed in the past week in five apparently unrelated massacres, including four shot Thursday near the border city of Ciudad Juarez. But the Mexico City shooting has raised alarm among residents about a drug war that has long seemed distant.

"Massacres have arrived" in Mexico City, El Universal newspaper declared. But Mexico City Attorney General Miguel Angel Mancera said he did not know if drug gangs were involved in the middle-of-the night shooting in Tepito, a working-class neighborhood just north of the colonial center.

Drug dealing is rampant in Tepito, but Mancera said there also have been problems with disputes among carjacking gangs.

Gunmen in a white SUV drove up just after midnight to a street of drab apartment buildings, corner grocery stores and auto repair shops, witnesses said. They jumped out of the car and gunned down six men in their 20s and 30s who had just gathered in front of a tiny convenience store. A seventh man was wounded.

People were still out on the streets when the shooting occurred. Drug dealing and robberies have been on the rise in the neighborhood but store owners still feel safe enough to keep their businesses open late. That in itself contrasts with border cities like Ciudad Juarez, where streets empty and many business close in the early afternoon for fear of drug-gang violence.

Several Tepito residents said they assumed the gunfire was fireworks for St. Judas Tadeo Day, commemorated with processions and street festivals across the city. As word spread, they slowly emerged from their apartments, shocked to find bodies face down in pools of blood.

"I've never seen anything so horrific happen. I go around at 2 or 3 in the morning and nothing has ever happened to me," said Guadalupe Ramirez, a 53-year-old grandmother walking past the site of the shooting. She said her 15-year-old grandchild had just returned from buying milk when the gunfire erupted.

The gunmen exchanged angry words with the young men before shooting, Mancera told the Televisa network. Bullet casings of two different calibers - 9 mm and .223 mm - were found at the scene, Mancera said, suggesting there were at least two gunmen.

Police were interviewing relatives and witnesses to determine the background of the victims and a possible motive. At least two of the victims had criminal records for robbery, Mancera later told reporters without elaborating.

"We would like to reassure the population that we are going to find those responsible," Mancera said.

Neighbors said they didn't know if the six young men belonged to a criminal gang but that they routinely hung around on the street, drinking beer and using drugs.

"I'm thinking of never coming back because every day things get worse," said Juan Fernandez, 60, who travels more than an hour to Tepito to get to the only job he's been able to find - as a clerk at the convenience store nearest to the shooting.